Machine for dressing millstones



narran sra'ras retrasa carica,

S. WV. DRAPER, Ol SOUTH DEDHAM, AND R. M. DRAIER, OF BOXBOROUGH,

MASSACHUSETTS.

MACHINE FOR DRESSING MILLSTONES.

Specification of Letters Patent No. 14,859, dated May 13, 1856.

To all whomz't may concern Be it known that we, S. lV. DRAPER, of South Dedham, in the county of Norfolk and State of Massachusetts, and R. M. Daarna, of Boxborough, in the county of Middlesex and State of Massachusetts, have invented certain new and useful Improvements in Machinery for Dressing Millstones; and we do hereby declare that the following is a full, clear, and exact description of the same, reference being had to the accompanying drawing, forming part of this specification, in which Figure l, is a plan of a machine with our improvements. Fig. 2, is a vertical section of the same, in the line as, y, of Fig. l.

Similar letters of reference indicate corresponding` parts in both figure-s.

This invention consists in certain improvements on the machine for dressing mill-stones which is the subject of Letters Patent granted to us May 25th, 1852.

Our improvement consists in a certain mode of actuating the pick for the purpose of causing it to strike with the same force throughout in cutting a long series of parallel furrows.

To enable those skilled in the art to make and use our invention, we will proceed to describe its construction and operation.

Our improvements are as follows: lnstead of having the bed-piece, A, which carries the pick shaft, F, cast with the circular head-piece, B, and only capable of moving with the said head-piece in a circle; it is attached to a sliding-piece, A, which is fitted to slide in a straight grooved way, B', which is arranged tangentially to and permanently attached to the head-piece. This sliding piece carries a short upright shaft, c, provided with a loose pinion, a, which gears with a fixed rack, b, on one side of the way B, and to this pinion is secured a bevel gear, (Z, which gears with another gear, e, on a shaft, f, which is arranged parallel with the bed, A. The bed, A, is supported partly by the sliding-piece, A, and partly on a small standard, A2, near one end. By turning the shaft, f, by hand, rotary motion is given to the bevel gear, (Z,

which, through the pinion, a, and rack,

gives a longitudinal movement to the sliding-piece, A, and 1n this way after a straight furrow or thread has been made by the movement of the pick along the shaft, ll, as in our former machine, the bed, A, with the pick, can be moved to make a new thread or furrow without turning the head-piece, B, thus keeping the pick shaft in a parallel position and producing parallel threading.

In order to enable the direction of the threading to be varied, the bed, r is made movable on a pivot, g, which is secured in the sliding-piece A. lVlien adjusted at the required angle to the sliding-piece, it is secured partly by a nut, h, on the pivot, g, and partly by a screw, z', which passes through a slot in a stay, j, attached to the bed, and screws into a small post, on the slide A. The bed, A, is slotted longitudinally, in order to enable it to be adjusted in that direction upon the pivot, g, and to work on either side of the head piece, B. The stay, j, must not move longitudinally with the bed, and therefore it is made detached and fits to the longitudinal slot of the bed, with a feather, r, which gives it rigidity laterally. In order that the feed movement of the sliding-piece, A', may be produced in all positions of the bed, A, and the shaft, f, the bearing, Z, of the shaft is carried by the upright shaft, c, which turns freely as a swivel, with any movement of the bed on the pivot, g. The bevel gear, e, fits to the shaft, 7, with a feather and groove to allow the shaft, 7, to slide, to admit of the longitudinal adjustment of the bed, the hub of the bevel gear being the immediate bearing for the shaft and the said hub fitting to the swivel bearing, Z, in the shaft, c.

ln order to operate the pick shaft, F, from the cam, G, which fits to the top of the mill spindle, in an effective manner in all the changes of position of the sliding-piece A, and at the same time to preserve a uniformity of the force of the blow, we have inverted the cam from the position described in the specification of our former Letters Patent above referred to, and have applied a secondary lever, m, between the said cam and the arm, c, of the pick shaft to throw up the said arm and lift the hammer. The fulcrum, m, of this secondary lever is attached to one side of the sliding-piece, i so that the lever must always bear the same relation to the said arm, c', and the said lever crossing the cam on one side of its center as shown in dotted lines in Fig. l, is capable of having a very considerable longitudinal movement without changing its effective relation with the cam owing to the inclined projections, s, s, of the cam being of the same height from their innermost to their outermost extremities as shown in Fig. 2. To increase and graduate the force of the blow of the pick (l a spiral spring, n. is applied to act upon an arm, n, on the pick shaft,the said spring being wound around a rod connected with a lever, m2, which is adjustable by means of a wedge attached to a rack, 0, which is moved by a sector lever, p, to throw the .wedge more or less under the lower arm of the lever and thus throw the upper arm more or less forward to give more or less force to the blow.

What we claim as our invenftion, and desire to secure byV Letters Patent, is,

ln combination with the inversion of the cam, G, we claim the employment of a secondary lever m, attached to the .sliding piece A', or arranged in any equivalent manner to cross the face of the cam on one side of the center', and transmit motion therefrom to an arm, c, on the pick shaft, whereby in all changes of the relative positions of the pick shaft and the cam, the pick is operated by the cam -in such a manner as to give a uniform force to the blow, as herein fully set forth.

SIMON W. DRAPER. REUBEN M. DRAPER.

Witnesses:

v FRANCIS CONANT,

ALBERT F. CONANT. 

